The present invention relates to a method of stimulating an immune response by using a hapten, in particular to a method of stimulating an immune response by using a hapten dried onto a solid support.
A hapten is a substance which can bind with an antibody, but is not capable of stimulating an immune response when presented alone. Most of the haptens are small molecular substances such as, e.g., drugs, hormones, small peptides and the like, that have a molecular weight lower than 1,000. However, if hapten is linked to a large molecule (which is used as a carrier) the hapten might then appear immunogenic. In order to stimulate an immune response by using a hapten, a conventional method comprises forming an analogue of the hapten, which contains a linking group (spacer arm) having a reactive group, for example, a carboxylic group, at its terminal end; binding the analogue to a carrier, usually a large molecule, for example a protein like BSA, by the reaction of the reactive group with, for example, the amino acid residues of the protein, to form a conjugate, and then stimulating an immune response of an animal and the animal's lymphocytes with this conjugate (Method Enzyme 70,85, 1980). This conventional method is complicated in that chemical synthesis steps are required. Furthermore, whether a hapten-specific immune response can be stimulated is dependent on various factors, such as, e.g., the length and the structure of the linking group, the binding site, the conjugation method, the physiochemical characteristics of the conjugate, the stability of the conjugate, and the ratio between the hapten and the carrier (J. Imm. Method 78:59, 1985; Imm. Methods, Acad. Press 137, 1979; J. Imm. Method 129:119, 1990; Method Enzyme 70:85, 1980; Immunoassays for Trace Chemical Analysis, Chapter 2, 1991). In addition, the immune response will not only react with the hapten, but also react with the linking group and the carrier, and therefore add to the difficulty in screening.